Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F297/00—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer
  • C08F297/02—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type
  • C08F297/04—Macromolecular compounds obtained by successively polymerising different monomer systems using a catalyst of the ionic or coordination type without deactivating the intermediate polymer using a catalyst of the anionic type polymerising vinyl aromatic monomers and conjugated dienes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
  • C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
  • C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
  • C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic monomers

Definitions

• the invention relates to a process for the preparation of copolymers of at least one conjugated diene and at least one vinyl aromatic compound comprising reacting the monomers in an essentially inert organic solvent and with the aid of an initiator based on lithium.
• the invention further relates to copolymers thus produced, represented by as well substantially random copolymers and as block copolymers, and to products further derived thereof such as blockcopolymers having substantially hydrogenated conjugated diene blocks and to compositions, containing the random copolymers such as unvulcanized compositions containing them, and to products containing to said random copolymers in a vulcanized state.
• substantially random copolymers are here meant copolymers in which more than 60% of the monomer units are arranged in an arbitrary manner.
• a general trend which can be derived from the contents of the above cited documents in relation to the solvent used in the polymerization processes described is that essentially any aliphatic, cycloaliphatic or aromatic compound or a mixture of these compounds can be used as solvent, provided that the compound is essentially inert.
• solvents are mentioned: a 50:50 weight ratio mixture of cyclohexane and isopentane (in 3), cyclohexane (in 7 and 8), hexane and cyclohexane or mixtures thereof (in 11 and 12).
• cyclohexane in 1,7,8,9,10,11,12
• a cyclohexane/n-hexane mixture 50:50 weight ratio in 4 and 5 and 30:70 weight ratio in 12
• a cyclohexane/isopentane mixture 50:50 weight ratio in 3 and 5
• benzene or heptane in 15
• hexane in 12
• toluene in 16
• Isopentane and n-hexane are known to be suitable for this purpose.
• polymerization rate constants have been found to be significantly higher than in similar polymerization processes using n-hexane/cyclohexane mixtures as solvent, which under similar conditions results in higher polymerization rates or alternatively results in a reduction of the monomer concentration in the reaction mixture.
• the solvency power of solvents consisting for at least 60 % by weight of cyclopentane was found to be at least as well as that of solvents consisting for at least 50 % by weight of cyclohexane during all stages of the polymerization process.
• any other inert aliphatic, cycloaliphatic or aromatic compound being mixable with cyclopentane and not interfering with the solvency power may constitute the remaining 40 or less weight percentages of the solvent, aliphatic and/or cycloaliphatic and/or aromatic compounds containing 6 or less carbon atoms being preferred, isopentane being the most preferred.
• the solvent consists for more than 80 %, more preferably for more than 95 %, by weight of cyclopentane.
• the solvents according to the present invention have been found to be suitable either in virtually any industrial solution polymerization process for the preparation of substantially random copolymers of conjugated dienes and vinyl aromatic compounds or in virtually any industrial polymerization process for the preparation of block copolymers of at least one conjugated diene and at least one vinyl aromatic compound and more particularly for the manufacture of linear, branched or star shaped block copolymers. For example by choosing a specific process type applying specific reaction conditions substantially random copolymers having the desired specific characteristics can be produced.
• Cyclopentane can be conveniently applied in processes disclosed in any of the cited documents 1 to 10. However, of all random polymerization processes the one as disclosed in cited document 2, i.e. British patent specification No. 1,283,327, is particularly preferred. Therefore according to a preferred embodiment of the present invention random copolymers are prepared by batch copolymerization of a conjugated diene and a vinyl aromatic compound with the aid of an initiator based on lithium in the presence of a solvent consisting for at least 60 % by weight of cyclopentane, in which embodiment (a) first a starting mixture is prepared from the diluent and part of the totally needed quantity of each of the monomers (b) subsequently the copo­lymerization is initiated by contacting this mixture with the initiator, and (c) during copolymerization the monomer ratio in the reaction mixture is kept constant (as hereinafter described) by addition of the remaining part of each of the monomers, while the heat of reaction is withdrawn by means of reflux cooling.
• step (b) as a rule the totally needed quantity of initator is added to the mixture mentioned under (a) under homogenization in a comparatively short time.
• step (c) is started approximately coincides with that at which the addition of initiator is stopped, but may be a little earlier or later.
• cyclopentane can be conveniently applied in processes, disclosed in e.g. the hereinbefore cited documents 20 to 24, for the manufacture of block copolymers.
• such a block copolymerization process is performed by a polymerization process with the aid of an initiator based on lithium in the presence of a solvent consisting for at least 60% by weight of cyclopentane comprising the well known sequential addition of monomer techniques, incremental addition of monomer technique or coupling technique as illustrated in e.g. the before-mentioned publications Nos. 25, 31, 32 and 33.
• the present process can be used to manufacture block copolymers containing tapered copolymer blocks by copolymerizing a mixture of conjugated diene and a vinyl aromatic compound utilizing the difference in their copolymerization reactivity rates as is e.g. known from the before-mentioned patent publications Nos. 24-27.
• symmetric and asymmetric radial and star block copolymers may be prepared as is known from the before-mentioned publications Nos. 20, 24 and 28-30.
• the block copolymers may be produced by anionic polymerization employing an organomonolithium initiator, preferably sec-butyllithium.
• the first step of the preferred embodiment of this process involves contacting the vinyl aromatic compound, preferably styrene, and the organolithium initiator in the presence of the solvent, therein forming a living polymer compound having the simplified structure A-Li and having a molecular weight between 2,000 and 100,000.
• the concentration of the initiator can be regulated to control the molecular weight. Generally the initiator concentration is in the range of about 0.25 to 50 milimoles per 100 grams of monomer and the polymerization reactions are usually carried out at a temperature in the range of -35 to 150 °C and at pressures which are sufficient to maintain the reaction mixture in the liquid phase.
• the living polymer in solution is contacted with a conjugated diene, providing a living polymer having a simplified structure A-B-Li.
• the living block copolymers C-Li may be prepared in a separate reactor or in the same reactor as the A-B-Li polymers. In that case, after the A-Li polymers are formed, additional initiator optionally may be added, whereafter the conjugated diene is added.
• a mean molecular weight of the complete coupled block copolymers is preferably 10,000 to 500,000.
• initiator based on lithium for these embodiments can be used e.g. alkyllithium compounds, such as methylenedilithium, isopropyl lithium, n.butyllithium, sec-butyllithium, amyllithium 2-ethylhexyllithium, phenyllithium, ethylenedilithium, trimethylenedilithium, pentamethylenelithium, 1,4-dilithiobenzene and the like.
• alkyllithium compounds such as methylenedilithium, isopropyl lithium, n.butyllithium, sec-butyllithium, amyllithium 2-ethylhexyllithium, phenyllithium, ethylenedilithium, trimethylenedilithium, pentamethylenelithium, 1,4-dilithiobenzene and the like.
• the copolymerization reaction according to both embodiments is preferably terminated by means of substances which kill the living polymer; this can be a proton releasing compound, for instance water, an alcohol, an amine or protonic acid, or, which is preferred, a coupling agent.
• a proton releasing compound for instance water, an alcohol, an amine or protonic acid, or, which is preferred, a coupling agent.
• the coupling can be effected conveniently by use of a difunctional coupling agent, for example 1,2 dibromoethane, or a diisocyanate providing a linear coupled copolymer or a tri-, tetra-, or other polyfunctional coupling agent for example the tetra-functional compounds silicon tetrachloride, stannic chloride, dimethyladipate and diethyladipate providing a non-linear or branched coupled copolymer.
• a difunctional coupling agent for example 1,2 dibromoethane, or a diisocyanate providing a linear coupled copolymer or a tri-, tetra-, or other polyfunctional coupling agent for example the tetra-functional compounds silicon tetrachloride, stannic chloride, dimethyladipate and diethyladipate providing a non-linear or branched coupled copolymer.
• the product of the coupling reaction consists partly of coupled copolymer and partly of
• the aromatic vinyl compound is preferably styrene, but may consist of another mono-vinyl aromatic compound for example: 1-vinylnaphthalene, 3,5-diethylstyrene, 4-n-propylstyrene, 2,4,6-trimethylstyrene, 4-phenylstyrene, 4-methylstyrene, 3,5-diphenylstyrene, 3-ethyl-1-vinylnaphthalene 8-phenyl-­1-vinylnaphthalene or a mixture thereof or mixtures containing predominantly styrene.
• 1-vinylnaphthalene 3,5-diethylstyrene
• 4-n-propylstyrene 2,4,6-trimethylstyrene
• 4-phenylstyrene 4-methylstyrene
• 3,5-diphenylstyrene 3-ethyl-1-vinylnaphthalene 8-phenyl-
• the conjugated diene is one capable of copolymerization with styrene or another aromatic vinyl compound and such that when polymerized with styrene or another selected aromatic vinyl compound or compounds, it provides a polymer having the desired properties.
• the diene is preferably 1,3-butadiene, but may be another diene, for example, 1,3-pentadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 2-methyl-1,3-pentadiene or 2,3-dimethyl-1,3-pentadiene or mixtures of them alone or with butadiene.
• two different preselected monomer ratios are applied: the monomer ratio in the mixture prepared beforehand in which the copolymerization is initiated and that in which the monomers are supplied after the initiation of the copolymerization.
• the monomer suppletion can take place by addition either of the monomers as a mixture prepared beforehand or of each monomer separately. Also the addition can be carried out continuously or portionwise.
• the monomer ratio and the monomer concentration in the reactor is kept constant or substantially constant which facilitates the control of the process. It is recommended that less than 90 % by weight of the totally needed quantity of the aromatic vinyl compound is used in the preparation of the starting mixture, the application of quantities smaller than 50 % by weight of the totally needed quantity of the aromatic vinyl compound being particularly preferred.
• reaction temperatures up to 95 o C are preferred.
• the preferred diene/aromatic vinyl compound weight ratio in the mixture in which the copolymerization reaction is initiated amounts to from 50:50 to 5:95.
• any monomer concentration can be applied preferably a total amount of monomer of at least 0.05 % by weight is used, total amounts of from 0.1 to 10.0 % by weight being particularly recommended.
• reaction mixture is intensively homogenized.
• homogenization is brought about by means of an intensively working stirrer.
• alkyllithium compounds such as methylenedilithium, isopropyllithium, n-butyllithium, sec-butyllithium, amyllithium, 2-ethylhexyllithium, phenyllithium, ethylenedilithium trimethylenedilithium, pentamethylenedilithium, 1,4-dilithiobenzene, 1,5-dilithiobenzene, 1,5-dilithionaphthalene and 1,3,5-trilithiumpentane.
• alkyllithium compounds such as methylenedilithium, isopropyllithium, n-butyllithium, sec-butyllithium, amyllithium, 2-ethylhexyllithium, phenyllithium, ethylenedilithium trimethylenedilithium, pentamethylenedilithium, 1,4-dilithiobenzene, 1,5-dilithiobenzene, 1,5-dilithiona
• the amount of initiator used in the process according to the present invention may vary within wide limits. In general 0.001-1.0 g of metallic or bound lithium per 100 g of monomer is applied. If required the copolymerization can be carried out in the presence of a slight amount of divinylbenzene or other substance that causes branching or cross-linking of the copolymer, prior to, together with or subsequent to the use of a coupling agent such as silicon tetrachloride, stannic chloride, a dihalogen hydrocarbon, a monoester such as ethylacetate, ethylacrylate or phenyl benzoate or a diester obtained by the reaction of a dicarboxylic acid with a monovalent alcohol, such as diethyladipate.
• a coupling agent such as silicon tetrachloride, stannic chloride, a dihalogen hydrocarbon, a monoester such as ethylacetate, ethylacrylate or phenyl benzo
• the process can be applied in combination with the use of polar organic compound for example as described in the British patent specification No. 884,490, which modifies the initiator in such a way that statistic copolymerization is promoted. In this way the microstructure of the diene part of the copolymer is changed to the effect that the 1,2-addition structure increases.
• the copolymer containing the reaction mixture is pumped to a polymer recovery area.
• the principal step in recovery of the polymer comprises coagulation and eventual drying of the polymer to produce a crumb.
• the cement may be coagulated by treatment with steam and/or hot water.
• the cement may be sprayed into a hot water bath under such condition that a crumb is formed.
• the solvent is removed as a vapour and may be recovered and recycled as desired.
• the resulting copolymer-water slurry is withdrawn and passed on to a dewatering screen where the water passes through the screen leaving the rubber crumb. This may be reslurried with cold water, drained and finally dried by known means.
• the invention further relates to products derived from the initially obtained substantially random copolymers or block copolymers.
• the random copolymers may be incorporated in unvulcanized compositions comprising a blend of said copolymer and other auxiliaries and particularly vulcanizing agents. These compositions can be transformed in shaped articles, e.g. tyres and subsequently vulcanized.
• the present invention is also relating to such unvulcanized compositions to shaped articles prepared from them and to vulcanized articles.
• Usual compounding ingredients are vulcanizing agents, vulcanization accelerating agents, vulcanization activating agents, antioxidants, fillers and extender oils which may be naphthenic, paraffinic or, which is preferred aromatic.
• the preferred vulcanizing agent is sulphur and the preferred filler is carbon black.
• Other examples of vulcanizing agents are 4,4′-dithiomorpholine and alkenyl phenoldisulphides.
• Examples of vulcanization activating agents which may be present are zinc oxide and stearic acid.
• Examples of vulcanization accelerating agents are cyclohexyl-2-benzothiazyl sulphenamide and 2-(4-morpholinyl-mercapto-)benzothiazole.
• the copolymer composition may further contain other inorganic fillers for example silica, bentonite, clay, titanium oxide, talc, diatomaceous earth, chalk and china clay.
• the present invention is also relating to products derived from the initially prepared block copolymers and in particular those copolymers the elastomeric mid block of which has been substantially hydrogenated and/or functionalized by conversion with reagents introducing a reactive group intended for further cross-linking in the final product, e.g. maleic anhydride.
• 1,3-Butadiene and styrene were copolymerized by means of sec-butyllithium as the initiator with the use of a purified diluent, consisting of a mixture of 80 percent by weight (pbw) of cyclopentane and 20 pbw of other aliphatics and cycloaliphatics containing 5 or 6 carbon atoms.
• the copolymerization was carried out in a reactor of 9 litres capacity, which was provided with an vigourous stirrer and which had been washed beforehand with the diluent, the air in the reactor having been displaced by dry oxygen free nitrogen.
• the reactor was filled with 5000 grams of the diluent mixture, 87.9 grams of styrene and 14.7 grams of butadiene. After the reactor charge had been heated to the required temperature (75 o C) while stirring intensively, the traces of initiator poison still present were rendered harmless by the slow addition of a small amount of sec-butyllithium solution to be used for the copolymerization till the start of an increase in temperature of the mixture could be observed.
• This initiator solution contained 200 mmol of sec-butyllithium per litre; the said small amount corresponds to 0.2 mmol of lithium compound.
• Examples 2, 3 and 4 and comparative examples A and B were carried out in the same manner as example 1, with the exception of variations in the process as can be derived from tables II, III, IV, V and VI respectively, showing details of experimental conditions as well as the data on the copolymers formed.
• Example 1 1- Composition of the reactor charge at the moment when the polymerization was initiated: diluent (cyclopentane 80 %)) 5000 g styrene 87.9 g butadiene 14.7 g sec-butyllithium 8 mmol 2- Polymerization conditions reaction temperature 75 o C rate of styrene supply 1.0 g/min rate of butadiene supply 3.18 g/min polymerization time 240 min 3- Coupling reaction diethyladipate (DEAP) 2 mmol coupling time 20 min 4- Copolymer formed Molecular weight (before coupling) 215000 1) Molecular weight (after coupling) 720000 Coupled portion of the copolymer 77 % Content of copolymerized styrene (after coupling) 23.8 %w Microstructure of the butadiene part of the copolymer cis-1,4 content 34.7 %w trans-1,4 content 55.3 %w 1,2 content 10.0 %w 1)
• Example 2 1- Composition of the reactor charge at the moment when the polymerization was initiated: diluent (cyclopentane 80 %)) 5000 g styrene 149.0 g butadiene 25.0 g sec-butyllithium 8 mmol 2- Polymerization conditions reaction temperature 75 o C rate of styrene supply 1.69 g/min rate of butadiene supply 5.36 g/min polymerization time 142 min 3- Coupling reaction diethyladipate (DEAP) 2 mmol coupling time 20 min 4- Copolymer formed Molecular weight (before coupling) 229000 1) Molecular weight (after coupling) 767000 Coupled portion of the copolymer 77 % Content of copolymerized styrene (after coupling) 23.6 %w Microstructure of the butadiene part of the copolymer cis-1,4 content 36.7 %w trans-1,4 content 55.5 %w 1,2 content 7.8 %
• Example 3 1- Composition of the reactor charge at the moment when the polymerization was initiated: diluent (cyclopentane 80 %)) 5000 g styrene 26.7 g butadiene 4.4 g sec-butyllithium 8 mmol 2- Polymerization conditions reaction temperature 90 o C rate of styrene supply 1.0 g/min rate of butadiene supply 3.18 g/min polymerization time 240 min 3- Coupling reaction diethyladipate (DEAP) 2 mmol coupling time 20 min 4- Copolymer formed Molecular weight (before coupling) 235000 1) Molecular weight (after coupling) 748000 Coupled portion of the copolymer 70 % Content of copolymerized styrene (after coupling) 24.9 %w Microstructure of the butadiene part of the copolymer cis-1,4 content 34.3 %w trans-1,4 content 56.6 %w 1,2 content 9.1 %w 1)
• Example 4 1- Composition of the reactor charge at the moment when the polymerization was initiated: diluent (cyclopentane 80% !) 5000 g styrene 58.5 g butadiene 9.7 g sec-butyllithium 8 mmol 2- Polymerization conditions reaction temperature 90 o C rate of styrene supply 2.19 g/min rate of butadiene supply 6.94 g/min polymerization time 110 min 3- Coupling reaction diethyladipate (DEAP) 2 mmol coupling time 20 min 4- Copolymer formed Molecular weight (before coupling) 218000 1) Molecular weight (after coupling) 730000 Coupled portion of the copolymer 71 % Content of copolymerized styrene (after coupling) 23.5 %w Microstructure of the butadiene part of the copolymer cis-1,4 content 36.0 %w trans-1,4 content 56.8 %w 1,2 content 7.2 %w
• Styrene-butadiene styrene block copolymers were prepared on a 1 kg scale according to a two stage polymerisation procedure followed by coupling of the linear living block copolymer with 1,2-dibromoethane (DBE) as coupling agent in one reactor.
• DBE 1,2-dibromoethane
• the solvent mixture Prior to its use in the polymerization experiments, the solvent mixture was pumped over Al2O3[Alcoa F7 (trademark) activated at 170 °C for at least 24 hours] to remove any polar compounds and stored under dry and oxygen free nitrogen.
• Al2O3[Alcoa F7 (trademark) activated at 170 °C for at least 24 hours] was carried out after the traces of initiator poison still present were eliminated by slow addition under vigorously stirring of a small amount of sec-butyllithium solution to be used for the polymerization until the start of an increase in temperature of the mixture could be observed.
• This initiator solution contained 200 mmol of sec-butyllithium per litre. 18.5 mmol of sec-butyllithium was subsequently added and the polymerization was performed at a temperature of 60 °C during 40 minutes.
• the obtained "living" polymer was coupled with 1.74 g DBE in 30 minutes.
• the obtained reaction mixture was stabilized after coupling by using Ionol (trademark).
• the resultant polymer cement was worked up, either alone or in a two batch blend by steam coagulation, using a laboratory type steam reactor.
• the wet polymer crumbs were dried at 90 °C for 2 hours in an oven with forced air circulation.
• styrene-isoprene-styrene block copolymer was prepared, starting from 148 g styrene in 6 l of the herein before-mentioned solvent, using 13.5 mmol sec-butyl lithium and 852 g of isoprene supplied in 20 minutes. Coupling was carried out with 1.28 g of DBE.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Graft Or Block Polymers (AREA)
• Polymerization Catalysts (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerisation Methods In General (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=10661721

Family Applications (1)

Country Status (7)

Cited By (1)

Families Citing this family (12)

Citations (2)

Family Cites Families (18)

• 1989
  • 1989-08-16 GB GB898918702A patent/GB8918702D0/en active Pending
• 1990
  • 1990-08-13 IN IN813DE1990 patent/IN180176B/en unknown
  • 1990-08-14 CA CA002023218A patent/CA2023218C/en not_active Expired - Fee Related
  • 1990-08-14 JP JP21488690A patent/JP3281366B2/ja not_active Expired - Fee Related
  • 1990-08-15 DE DE69033196T patent/DE69033196T2/de not_active Expired - Fee Related
  • 1990-08-15 EP EP90202213A patent/EP0413403B1/de not_active Expired - Lifetime
  • 1990-08-15 US US07/567,843 patent/US5336737A/en not_active Expired - Lifetime

Patent Citations (2)

Non-Patent Citations (4)

Also Published As

Similar Documents

Legal Events